Robert Kubica on Thursday said he is reserving his judgement about a Red Bull-like exhaust layout that will debut on the Renault car this weekend.

Robert Kubica on Thursday said he is reserving his judgement about a Red Bull-like exhaust layout that will debut on the Renault car this weekend.

Like Ferrari and Mercedes, the Enstone based team has also readied a 'blown' exhaust setup - as seen on Red Bull's RB6 this year - in time for Valencia, opening up a bigger channel of air and also directing the engine fumes through the double diffuser.

But Pole Kubica, the highest-scoring runner in a car other than a McLaren, Red Bull, Ferrari or Mercedes, told reporters about the update in Spain: "It's quite a complex thing to make it work and it's not so easy.

"So there might be some positive effect but also some negative effects, we'll have to see."